Cannabis and Testosterone: New Study Flips the Script
6/4/2026
5 min read
By The TRT Catalog
A 2026 University of Geneva study found cannabis users had 23% higher testosterone, not lower. What it means for TRT, fertility, and what to tell your clinic.
Key Takeaways: A 2026 University of Geneva study published in Communications Medicine found that young men who used cannabis had roughly 23% higher testosterone than non-users -- the opposite of the long-repeated claim that weed lowers testosterone. The increase was traced to the testes themselves. But this was a small cross-sectional study of 94 men aged 18-23, it does not prove causation, and the researchers were clear that higher testosterone does not mean better fertility. If you are wondering whether cannabis is helping or hurting your hormones, the only way to know your actual levels is a blood test -- not a headline.
"Does weed lower testosterone?" is one of the most-searched questions in men's health, and for years the assumed answer was yes. That assumption took a hit in 2026.
A study from the University of Geneva, published May 28, 2026 in the Nature-family journal Communications Medicine, found that young men who used cannabis had approximately 23% higher testosterone than non-users [1][2]. Not lower. Higher. And the researchers were able to pinpoint where the extra testosterone was coming from.
This does not mean cannabis is a testosterone booster, and it does not mean it is safe for your hormones. But it does mean the conventional wisdom was built on shakier ground than most people assumed -- and the real story is more complicated than either side of the debate wants it to be.
What the Study Actually Found
The researchers analyzed plasma samples from 94 young Swiss men (conscripts aged 18 to 23): 47 cannabis users and 47 matched non-users [1][2]. They measured seven major sex hormones using high-precision mass spectrometry.
The headline findings [1][2]:
Testosterone was about 23% higher in cannabis users compared to non-users.
The increase was traced to the testes -- specifically the Leydig cells, the cells responsible for producing testosterone -- rather than to changes in brain-level signaling alone.
Two progesterone-derived metabolites, 11B-hydroxyprogesterone and 5B-dihydroprogesterone, were sharply elevated in cannabis users. The researchers proposed these as potential new biomarkers for detecting regular cannabis use.
The senior researcher, Serge Rudaz of UNIGE's Section of Pharmaceutical Sciences, and lead author Mathieu Galmiche framed the result carefully: cannabis "appears to alter steroid metabolism in young men," but what that means clinically "still needs more work" [1].
Why This Contradicts What You've Heard
For decades, the prevailing message was that cannabis suppresses testosterone. That came from a mix of older animal studies and small, inconsistent human studies -- some showing acute drops in testosterone after THC exposure, others showing no effect, and almost none using the rigorous hormone measurement methods available today.
The Geneva study stands out for three reasons:
Precision measurement. It used mass spectrometry to quantify multiple hormones at once, rather than the less specific immunoassays many older studies relied on.
A clean comparison. Users and non-users were matched young men from a single conscription population, reducing some of the lifestyle confounding that muddies broader survey data.
It located the source. By identifying the testes as the origin of the increase, the researchers moved beyond a simple correlation toward a biological mechanism.
This aligns with a broader 2026 reassessment. A separate analysis covered in the press concluded that cannabis use "does not lower testosterone" and may even increase its testicular synthesis [2]. The simple "weed kills your T" narrative does not hold up to the newest evidence.
Before anyone treats this as permission to light up for hormonal gains, the limitations are significant -- and the researchers said so themselves.
It is cross-sectional. This is a snapshot comparison, not a controlled trial. It cannot establish that cannabis causes higher testosterone. As the authors noted, the increase could reflect a compensatory response, or the reverse causation that men with naturally higher testosterone are more likely to use cannabis because of associated risk-taking behavior [2].
The sample is small and narrow. 94 men, all aged 18 to 23, all from Switzerland, all with presumably healthy testes. This tells you very little about a 45-year-old man with age-related or obesity-related testosterone decline -- the exact population most likely to be researching testosterone decline with age and considering treatment.
Dose and frequency were not detailed. The study did not clearly report how much or how often participants used cannabis, or measure THC directly, which limits any practical dosing interpretation.
Higher testosterone is not the same as better health. This is the caveat the researchers stressed hardest.
What It Means for Fertility
Here is where the "more testosterone is good" instinct breaks down completely. The researchers were explicit: the elevated hormone levels in cannabis users should not be interpreted as an indicator of sperm quality or fertility [1][2].
The relationship between circulating testosterone and fertility is genuinely complex. In fact, exogenous testosterone -- the kind used in testosterone replacement therapy -- famously suppresses sperm production by shutting down the body's own signaling, which is exactly why men who want to preserve fertility on TRT use HCG or consider enclomiphene instead of standard TRT.
Prior research on cannabis and semen quality has been all over the map. A 2026 North American preconception cohort study found no strong link between cannabis use and semen parameters, while older studies have reported reduced sperm concentration and motility with heavy use. The honest summary: the data is inconsistent, and this study does nothing to resolve it.
If you are trying to conceive, a 23% testosterone difference is not a green light. A semen analysis and a conversation with a clinician are worth far more than any single hormone number.
What This Means If You're on TRT or Considering It
For men already on or evaluating testosterone therapy, the practical takeaways are straightforward.
Disclose cannabis use to your clinic. Because cannabis appears to modestly raise testosterone and clearly alters steroid metabolism, it can affect how your bloodwork reads -- especially borderline results. A good clinic interprets your numbers in context, and they cannot do that if they do not know. Telehealth TRT providers screen for substance use as a standard part of safety evaluation; honesty produces a more accurate baseline.
Do not treat cannabis as a testosterone strategy. A modest, unproven association in healthy young men is not a substitute for diagnosis and treatment. If you have symptoms and your total testosterone is consistently below 300 ng/dL on two morning draws, that is a clinical issue that lifestyle tweaks rarely fix on their own. The diagnostic process matters more than any single input.
Keep the rest of your inputs in order. Cannabis is one variable among many. Sleep, body composition, alcohol, and stress all move testosterone -- some of them far more than a single modestly-powered cannabis study suggests. We cover the evidence-based levers in TRT vs. natural optimization and the realities of alcohol and TRT.
If you have symptoms of low testosterone and want a real answer rather than a headline, an online TRT clinic can coordinate comprehensive bloodwork and physician evaluation without the months-long wait for an endocrinology referral. When choosing a clinic, look for providers who run a full hormone panel -- total and free testosterone, SHBG, estradiol, LH, and FSH -- rather than a single total testosterone number, and who take a full lifestyle history (cannabis included) before recommending therapy. You can compare clinics side by side to see who actually does this.
The Bottom Line
The 2026 Geneva study is a useful correction to a tired myth: the claim that cannabis reliably tanks your testosterone does not survive contact with rigorous data. In young, healthy men, cannabis use was associated with higher testosterone, traced to the testes.
But "higher" is not the same as "better," an association is not causation, and a study of 94 young men is not a treatment plan. The finding is interesting, biologically intriguing, and genuinely newsworthy. It is not a reason to change your hormone strategy.
The only number that tells you what is actually happening in your body is your own bloodwork. If you are concerned about your testosterone -- whether you use cannabis or not -- get tested, disclose your full history, and make decisions from data rather than headlines.
References
University of Geneva (UNIGE). "Cannabis Use Does Not Lower Testosterone." UNIGE Media, May 28, 2026. unige.ch
Galmiche M, et al. "Cannabis use and steroid hormone profiles in young men." Communications Medicine, May 28, 2026. DOI: 10.1038/s43856-026-01469-x.
"Weed Linked to Higher Testosterone Levels in Young Men." U.S. News & World Report, June 1, 2026. usnews.com
Joseph L, et al. "A North American preconception cohort study of cannabis use and semen quality." Andrology, 2026. DOI: 10.1111/andr.70056.
The newest and most rigorous data says no -- and may suggest the opposite. A 2026 University of Geneva study published in Communications Medicine analyzed plasma from 94 young Swiss men (47 cannabis users, 47 non-users, aged 18-23) and found cannabis users had approximately 23% higher testosterone than non-users. The researchers traced the increase to the testes themselves, specifically the Leydig cells that produce testosterone. This contradicts the long-repeated claim that marijuana suppresses testosterone, which was based largely on older, smaller, and inconsistent studies. That said, this was a cross-sectional study -- it shows an association, not proof that cannabis raises testosterone. The clinical meaning is still unsettled, and higher testosterone does not automatically mean better health or fertility.
Will smoking weed raise my testosterone enough to skip TRT?
No. A 23% difference in a population of healthy 18-to-23-year-olds with normal hormones is not the same as a treatment effect, and it is nowhere near what testosterone replacement therapy produces in a man with clinical hypogonadism. If your total testosterone is consistently below 300 ng/dL on two morning blood draws and you have symptoms -- low libido, fatigue, difficulty building muscle, brain fog -- cannabis is not a substitute for medical evaluation and treatment. The study population was young men with presumably healthy testes; the finding tells you little about whether cannabis would meaningfully change levels in an older man with age-related or obesity-related decline. Get tested before assuming any lifestyle factor fixes a hormone deficit.
Does cannabis affect fertility or sperm count?
Higher testosterone in this study did not translate to better fertility, and the researchers were explicit about that. The link between blood testosterone and sperm quality is complex, and prior research on cannabis and semen parameters has been mixed -- some studies show reduced sperm concentration and motility with heavy use, others show little effect. A 2026 North American preconception cohort study found no strong association between cannabis use and semen quality. The honest answer is that the data is inconsistent, and a 23% testosterone difference should not be read as a fertility benefit. If you are trying to conceive, cannabis is one of many variables worth discussing with a clinician, alongside a semen analysis.
Should I stop using cannabis before a testosterone blood test?
Tell your clinic you use cannabis, but you generally do not need to stop before testing. Because cannabis may modestly raise testosterone and alters steroid metabolism, disclosing use helps your provider interpret your results accurately -- especially borderline readings. Standard testing protocol still applies: two separate morning draws before 10 AM, fasting, ideally on a day when you are not acutely intoxicated. The bigger issue is honesty: telehealth TRT clinics screen for substance use as part of safety evaluation, and concealing regular cannabis use can lead to a less accurate picture of your baseline.
How does cannabis change testosterone in the body?
The Geneva researchers located the source of the testosterone increase in the testes, specifically the Leydig cells, suggesting cannabis directly alters how those cells synthesize hormones rather than acting only on the brain's signaling. They also identified two progesterone-derived metabolites -- 11B-hydroxyprogesterone and 5B-dihydroprogesterone -- that were markedly elevated in cannabis users and could serve as biomarkers of regular use. The mechanism is not fully understood, and the researchers noted the increase could also reflect a compensatory response, or that men with naturally higher testosterone are simply more likely to use cannabis. Causation has not been established.
